Sterile disposable medicament administration system

ABSTRACT

A medicament administration system is provided that can be used once, and then discarded, and that can be used in conjunction with a syringe pump without danger of an embolism, comprising a twin valve T-connector, an air eliminator, and an administering means such as a needle for connection to a patient. A syringe can also be included as an integral part of the system and an administration system combining the syringe is a preferred embodiment. All interconnected components are sterile, and disposable. Another optional but preferred feature is an air spring or cushion that absorbs peak pressures arising from pumping action of the syringe plunger, and that is associated with the air eliminator at its upstream side. A visual flow indicator can also be included as a component.

United States Patent Rosenberg [4 1*Mar. 21, 1972 STERILE DISPOSABLE MEDICAMENT ADMINISTRATION SYSTEM David Rosenberg, Glen Cove, NY.

Pall Corporation, Glen Cove, N.Y.

The portion of the term of this patent subsequent to Aug. 11, 1987, has been dis claimed.

Filed: Jan. 8, 1970 Appl. No.: 1,499

Related U.S. Application Data Continuation-impart of Ser. No. 643,093, June 2, 1967, Pat. No. 3,447,479, Continuation-impart of Ser. No. 710,609, Mar. 5, 1968, Pat. No. 3,572,375, Continuation-in-part of Ser. No. 718,088, Apr. 2, 1968, Pat. No. 3,523,408, Continuation-impart of Ser. No. 787,539, Dec. 27, 1968, abandoned.

Inventor:

Assignee:

Notice:

U.S. Cl ..55/159, l28/2l4.2 Int. Cl ...B01d 19/00, A61m 5/00 Field of Search ..55/35, 97, 159, 96, 171;

References Cited UNITED STATES PATENTS 9/1954 Gobel 1 28/2142 3,066,462 l2/ 1962 Yap et a1. ..55/97 3,279,653 10/1966 Pfleger .128/214 3,300,949 l/1967 Smylie et a1. .....55/35 3,364,658 l/I968 Walker ..55/171 3,523,408 8/1970 Rosenberg ..55/159 FOREIGN PATENTS OR APPLICATIONS 989,642 4/1965 Great Britain ..92/1 3.7

Primary Examiner-Charles N. Hart Attorney-Janes and Chapman [57] ABSTRACT A medicament administration system is provided that can be used once, and then discarded, and that can be used in conjunction with a syringe pump without danger of an embolism, comprising a twin valve T-connector, an air eliminator, and an administering means such as a needle for connection to a patient. A syringe can also be included as an integral part of the system and an administration system combining the syringe is a preferred embodiment. All interconnected components are sterile, and disposable.

Another optional but preferred feature is an air spring or cushion that absorbs peak pressures arising from pumping action of the syringe plunger, and that is associated with the air eliminator at its upstream side. A visual flow indicator can also be included as a component.

44 Claims, 16 Drawing Figures SHEET 1 [IF 5 FIG. 2

PATENTEDHARZI I972 9. 650, 093

sum 2 OF 5 63 6! 66 FIG. 3

PATENTEDHARZI I972 SHEET '5 [IF 5 STERILE DISPOSABLE MEDICAMENT ADMINISTRATION SYSTEM This application is a continuation-in-part of Ser. Nos. 643,093, filed June 2, 1967, now U.S. Pat. No. 3,447,479, 710,609, now U.S. Pat. No. 3,572,375 filed Mar. 5, 1968, 718,088, now U.S. Pat. No. 3,523,408 filed Apr. 2, 1968, and 787,539, filed Dec. 27, 1968 and now abandoned.

This invention relates to a sterile disposable medicament administration system for administration of medicaments to a patient, and, more particularly, to a system comprising a combination of a visual flow indicator, a twin valve T-connector, an air eliminator, and a means for delivery of medicament to a patient, and as a part of the combination, or adapted to be used therewith, a syringe operable by an electric drive for pumping of the medicament.

Administration systems in use for administering medicaments to a patient are surprisingly complex and cumbersome, and are usually arranged for manual or gravity operation. Despite the advances in modern medical science, such systems are very little changed from those in use a generation ago, and, needless to say, they consequently are far from satisfactory.

A perennial problem is that of ensuring sterility of all of the components. Since the more costly components necessarily have to be reused, this involves washing, and sterilizing, which in turn requires time, equipment, and manpower. Because of the danger of an embolism, the system has to be painstakingly cleared of air before use, and has to be airtight. In the systems available, this has meant that electric pumps cannot be used, partly because of the insurmountable sterilization problems created by the available pump designs, and partly because of the danger of air being sucked into the system and administered before the pump can be stopped. A further problem is the surge and fall of pressure during the pressure and exhaust strokes of a pump, which increases the likelihood of air being drawn into the system in use.

A disposable system that could be made up as a unit, sterilized as a unit, used, and then discarded would resolve these problems. However, it has been impossible to design such a system, for marketing at a reasonable cost, because of the unavailability of the necessary components. Moreover, a system that could be used with a pump has been quite beyond reach, because of the need for an air eliminator, an air spring or pressure absorber, and appropriate one-way valving.

It is known that porous materials of a small pore size when wetted by a liquid are incapable of passing gases at fluid pressures below the so-called bubble point of the material. The bubble point is defined as the characteristic pressure at which the first bubble of air appears, when such a material is pressurized with air while immersed just under the surfaceof a liquid. The bubble point effect is well known from U.S. Pat. No. 3,007,334, dated Nov. 7, 1961. In fact, the method and apparatus according to that patent make it possible to determine the maximum pore size of filter elements from the pressures at the bubble point, since these pressures are directly correlated with the pore size of the filter.

It has been proposed that this phenomenon be employed to prevent the passage of air to patients, by insertion in the administration line leading to the patient of a microporous filter material which is preferentially wetted by the liquid being administered. Such a device when saturated with liquid will not permit the passage of air to the patient,- so long as the fluid pressure is below the bubble point of the filter. However, the problem with such devices is that although they block the passage of air, they do not vent it, with the result that the air held back by the filter can cover the surface of the filter, restricting flow, or even blocking it, if the surface is completely covered, and increasing the pressure drop across the filter, with the result that the bubble point of the filter element can be reached sooner than expected, after which the blocked air will pass through, virtually all at once. Furthermore, the presence of this type of filter in the line makes it difficult if no impossible to clear the line of air once the filter has been wetted, which means that after the line has been used, it must be thoroughly dried out so as to dry the filter, before it can be cleared of air for the next use. This drying procedure is not always feasible, however, particularly where filters must be steamed, sterilized, or hot-water sanitized before use, and are therefore wetted completely before use.

The problem is particularly troublesome with microporous filter materials having pores of less than one micron in diameter. Such filters are intended to filter out harmful micro-organisms from fluids, but in such filters the pressure differential needed to force air through a filter wetted with a liquid can be as high as 30 p.s.i.d., as a result of which complete filter blockage can result from the presence of air in sutticient quantity in the system to cover the surface of the filter.

It is possible to avoid these difficulties to a certain extent by the use of filter materials that contain both hydrophobic and hydrophilic portions. The hydrophilic portions will pass the water, and the hydrophobic portions will not be wetted by water, and will therefore remain open for passage of gas therethrough. Such filters will pass air and other gases, but of course they cannot be used in medical applications or other medicament to pass through a conventional pump, for sanitary reasons. A syringe pump presents itself as a feasible alternative. Surgical syringes are available, and can accurately meter fluid. Moreover, since they employ a piston and cylinder, they have proved suitable for accurately pumping measured small amounts of fluid for laboratory use.

One such laboratory syringe pump is shown by Wiley et al. in U.S. Pat. No. 3,259,077. Wiley et al. disclose a pump assembly which employs a surgical syringe as the means for pumping measured amounts of fluid. However, the valve assembly that is associated with the system is rather complicated, and the pump itself relatively expensive to manufacture. Moreover, the syringe is a part of the assembly, which is adapted to readily employ only syringes of a fixed size. It is clearly not practical to have several pumps of several sizes for each size syringe, and it is also necessary to sterilize the syringe after each use, but Wiley et al. make no provision for this.

Another essential component, if a syringe pump is to be used, is a check valve arrangement to ensure one-way flow through the system, to and from the syringe. This is a special problem in itself.

Syringes of course are widely used in medicine for the injection of fluids into the body, or for withdrawal of fluids from the body. Frequently, the volume of fluid that is to be injected or withdrawn is greater than the available capacity of the syringe. This requires two or more injections or withdrawals, with a corresponding number of insertions of the syringe needle into the body.

In order to avoid this problem, Y-couplings have been provided, such as are described in U.S. Pat. No. 986,263 to Bevill, patented Mar. 7, 191 l, which permits the connection of the syringe to an additional reserve container. The coupling is provided with valves, to regulate the flow of fluid in the proper direction, and prevent any backflow thereof, and these valves are connected with the Y-coupling by a section of flexible tubing. This device is large and clumsy, however, and has never been widely employed, partly because it is really only useful with syringes of very large volume, whereas the problem most frequently is encountered when the syringes have a very small volume. In such cases, the Bevill device is virtually useless.

In accordance with the invention, there is provided a sterile disposable administration system that is especially designed for use with a syringe pump of a unique design to permit use of a variety of types and sizes of syringe, and that prevents administration of air into a patient, due to the combination in the system of an air eliminator and, optionally, an air spring to take up pressure surges arising from pumping action of the syringe. The air spring can also ensure a steady delivery of medicament at the needle, despite the intermittent pumping action of the syringe pump, at appropriately selected relative needle and syringe sizes. The system also features a twin valve T-connector of a special design, to ensure one way flow with a minimum of fluid volume lost in valving, as well as a visual flow indicator and a delivery means for administering the medicament to a patient. I

The disposable system accordingly comprises, in combination and in series, a twin valve T-connector for attachment for a supply reservoir, an air eliminator, an air spring (which is optional, but is preferred), and a delivery means, all interconnected by fluid delivery tubing, in an airtight manner. A syringe having a plunger adapted to be reciprocated by a pump drive preferably is included as an integral part of the disposable system, but if not, the system is adapted to be attached thereto by the user, at the T-connector. A visual flow indicator can also be included as a component, upstream of the T-connector.

The essential components of this system are themselves novel, and never previously available, and their special design is what makes this system both sterile and disposable, as well as being adapted for safe automatic administration of medicaments by a pump. These essential components are the T-connector and the air eliminator, and the syringe, as adapted for use with a pump and the air spring can also preferably but optionally be included.

The twin valve T-connector combines in one unit a coupling body having three passages therethrough that are interconnected, and two check valves, one each in two of the passages, ensuring that flow of fluid through such passages of the connector proceeds only in one direction. The T-connectoris one unit, having one or a plurality of parts that are fitted and secured together in a unit construction, with the valves fixed in the two passages therein in a leak-tight manner, and lends itself to fabrication by molding or casting to a predetermined shape. This not only simplifies the manufacture of the T-connector, but also makes it suitable for mass production, and thus reduces its cost to a minimum.

in a preferred embodiment of this device, the coupling is made entirely of plastic, with the exception of the check valves, which can be of a plastic or rubber material, and the plastic components of the coupling are all united together, with the check valves locked in position, and with mating and/or standard fittings, joints or sockets in each of the three passages, for coupling thereof to a syringe of conventional construction, a delivery means, and a receptacle or fluid supply. A preferred type of mating joint or socket is a Luer fitting or Luer-Lok.

The invention accordingly provides as one feature a twin valve T-connector for coupling a syringe to a liquid medicament supply, for delivery to a body via a fluid delivery device of a volume of liquid medicament in excess of the capacity of the syringe, comprising, in combination, a coupling body having three interconnected passages therethrough, check valves, preferably of the duckbill jaw type, in two of said passages, controlling flow of fluid therethrough in a single direction, and means at an outer portion of each passage adapted for connection of said passage and the coupling to at least one member selected from the group consisting of a liquid medicament supply container, a fluid delivery device, and a syringe, the body being formed of plastic and holding the valves therein as one unit.

A feature of the T-connector according to the invention is its extremely small internal volume or fluid retention. This is usually less than 1 cc., and is preferably less than 0.1 cc. This means that quite high operating pressures can be achieved using conventional medical syringes, and also that very little of the fluid being delivered or withdrawn is wasted within the T- connector.

A further feature is that it can be made of a rigid, non-pressure-deformable material, which means that none of the available fluid pressure delivered via the syringe is lost in distending the connector.

The T-connector also includes in a preferred embodiment a resilient foam spring which holds the jaws of the check valve in the fluid delivery passage closed, but with sufficient resilience to permit their opening under a predetermined fluid pressure, and nonetheless preventing leakage through the valve at lower fluid pressures.

The twin valve T-connector of the medicament administration system of the invention and any syringe combined therewith or to which it is adapted to be attached are adapted to fit as components of a syringe pump assembly, to which they can be readily attached or detached, for quick use. Moreover, this syringe pump assembly needs only one drive mechanism, and yet can function with any of a large array of medicament administration systems with syringes of different sizes, whether the syringes are included as an integral part of the system, or attached thereto at the T-connector by the user.

The syringe pump assembly comprises a base; a fluid line; a syringe having a body portion; a pumping plunger reciprocably movable between limits in the body portion; and an aperture in the body portion communicating with the fluid line for receiving fluid from and discharging fluid to the fluid line upon reciprocation of the plunger; means holding the syringe on the base, preferably in an easily-detachablemanner, and adapted to accommodate syringes of different sizes; a twin valve T-connector of the administration system of the invention, communicating with the syringe such that fluid can proceed through the medicament administration system in only one direction, whereby fluid is pumped therethrough upon reciprocation of the plunger; and drive means operatively connected to the plunger for reciprocably moving the plunger within the syringe body to pump the fluid in the administration system.

The air eliminator is capable of separating gases and liquids and of venting the gas. in this way, blockage of the administration system by the buildup of an air lock is avoided, while at the same time the entrained air is entirely eliminated from the liquid. Thus, the device of the invention is particularly adapted for medicinal applications, where air must be vented from the administration system, and must also be absolutely prevented from reaching a patient receiving an injection of the fluid. in a preferred embodiment, the device also is capable of removing harmful y micro-organisms, so that the liquids and/or gases passing through he administration system are sterilized at the same time.

The air eliminator in accordance with the invention comprises, in combination, a housing; a chamber in the housing of which chamber one wall comprises a filter material that is wetted by a liquid to be passed through the housing, and another wall comprises a filter material that is not wetted by the liquid passing through the housing, but in fact is liquidrepellent; an inlet in the housing for delivering fluid comprising air and liquid to the chamber between the liquid-wetted and liquid-repellent filter materials; a liquid outlet in the housing on the opposite side of the micrmorganisms,material; and an air outlet in the housing the the opposite side of the liquidrepellent material. Both the liquid-wetted and the liquid-repellent materials preferably have a pore size less than about 0.3 micron, at which harmful micro-organisms cannot pass therethrough. The housing and associated parts of the eliminator are preferably made of plastic, and are bonded or fused together in a one piece construction.

The air spring is associated with the air eliminator, and is normally connected to the chamber upstream of the liquidwetted and liquid-repellent filter materials. The air spring comprises an air-filled receptacle having as the only means of fluid access thereto a fluid connection to the upstream side of the air eliminator.

The several components of the sterile medicament administration system of the invention are easily assembled with or without the syringe (after preparation as described hereinafter) and interconnected by flexible tubing. The tubing can be attached to the fluid inlet and outlets provided on the components for this purpose, preferably bonded thereto by heat-fusing, solvent-bonding, or by an adhesive. The system is then sterilized in an oven or in a steam sterilizer, using the conventional sterilization techniques. It can then be sealed hermetically in a sterile package, and is ready for storage or shipment, and use whenever desired.

FIG. 1 represents a plan view of a complete sterile disposable medicament administration system of the invention, assembled and ready to attach to a syringe pump and supply bottle;

FIG. 2 represents a plan view of the system of FIG. 1, connected to a syringe pump and supply bottle, and ready for use;

FIGS. 3 to 14 represent detailed views of the essential components of the assembly of FIG. 1;

FIG. 3 is a view in cross section of a typical twin valve T- connector in accordance with the invention, employing duckbill check valves;

FIG. 4 is an end view, taken along the line AA of FIG. 3, and looking in the direction of the arrows;

FIG. 5 is a view of an embodiment of a syringe pump with the T-connector shown in cross section;

FIG. 6 represents an exploded view of one type of air eliminator in accordance with the invention, in which the liquid-wetted and liquid-repellent filter materials are at opposite sides of the chamber;

FIG. 7 is a top view of the air eliminator of FIG. 6 in assembled form;

FIG. 8 is a cross-sectional view of another embodiment in which the liquid-repellent and liquid-wetted filter materials are arranged concentrically;

FIG. 9 is a perspective view of the air eliminator of FIG. 8;

FIG. 10 is an end view of another embodiment of the eliminator of the invention;

FIG. 11 is a longitudinal sectional view of the air eliminator of FIG. 10, taken along the lines AA of FIG. 10, and looking in the direction of the arrows;

FIG. 12 is a cross-sectional view of the air eliminator of FIG. 10;

FIG. 13 is a cross-sectional view of another embodiment of the air eliminator in accordance with the invention, in a diskshape, with two gas vents at the sides ofthe disk;

FIG. 14 is a view of the air eliminator. of FIG. 13, looking at the side of the disk with the gas vents;

FIG. 15 is a view of the other side of the air eliminator of FIG. 13; and

FIG. 16 represents a plan view of another embodiment of medicament administration system of the invention, adapted for connection to a syringe, syringe pump and supply bottle.

The administration system of FIGS. 1 and 2 comprises a visual flow indicator 1, made of transparent flexible plastic, such as polyvinyl chloride, in tubular form, with the ends 2,3 pinched and permanently heat-sealed to a tube connector 4 for attachment to a supply bottle, and to a flexible tubing 5 which connects with a T-connector 10. The details of the T- connector are shown in FIGS. 3 to 4. The tubing Sis bonded in a leak-proof seal to the leg 11 of the T-connector, in which is disposed a check valve 12, in this case,'a duck bill valve, which ensures that flow is only in one direction, towards the T-junction chamber 54 in the T-connector. To one of the other legs 14 of the T-connector is attached a syringe 20, which is adapted for insertion in a syringe pump 21, as is more particularly shown in FIG. 5.

The third leg 15 of the T-connector is attached to a tubing 16, which is bonded thereto a leak-proof seal. The tubing runs to the inlet 31 of an air eliminator 30, from which air is vented via the port 32. The details of the air eliminator are shown in FIGS. 6 and 7.

Attached to an inlet 33 of the air eliminator is an air spring or cushion 34, in the form of a dead end piece of flexible tubing, filled with air. As the syringe pump advances on its pressure stroke, with pumping movement of the plunger 22 of the syringe 20, a pulse of fluid pressure advances through the system, and its presence is indicated by an advance of fluid in the air spring 34, compressing the air in the spring. The degree of compression is proportional to the fluid pressure, and therefore the spring 34 can also serve as a pressure gauge, from which the pressure can be read off by appropriate gradations 35 of a pressure scale marked on the spring 34. This spring has the function of taking up the pressure surge, and equalizing pressure to some degree beyond the air eliminator 30. If the flow through the needle is low, the spring can even ensure a steady fluid flow through the needle, evening out the pressure surges in fluid flow from the syringe pump.

In operation, the tube connector 4 is attached to the stopper 6 of a supply bottle 7, as shown in FIG. 2, and the syringe 20 is fitted in the cradle of a syringe pump. The needle 41 is at this point unattached. The pump is started, whereupon fluid is pumped from the supply bottle 7 through the tubing 6, connector 4, visual flow indicator 1, tubing 5, T-connector l0, syringe 20, tubing 16, air eliminator 30, tubing 37, needle adapter 38 and needle 39, clearing air from the system. The needle is then inserted in the patient, and administration begun.

As the syringe pump delivers a volume of fluid via the T- connector through tubing 16, a comparable volume of fluid enters the air spring 34, compressing the air in the air spring, while fluid flow proceeds via the air eliminator at a reduced pressure through tubing 37 to the needle. The syringe pump on its suction stroke draws fluid from the supply bottle 7, and flow in tubing 16 ceases, whereupon fluid pressure drops. The compressed air in air spring 34 now exceeds fluid pressure in the air eliminator 30 and beyond, and forces fluid in the air spring into the air eliminator 30. Since the twin valve T-connector l0 prevents reverse flow in tubing 16, fluid flow continues in tubing 37 to the needle, now under the pressure of the compressed air in the air spring. If the volume of the air spring is sufficient, this flow can continue until the syringe pump has ended its suction stroke and begun its pressure stroke, so that a steady flow of fluid at the needle is obtained.

The visual flow indicator 1 is of conventional construction, and any type of such indicator can be used. It is preferably made of transparent material, although translucent materials can also be employed, and is best made of plastic or glass, such as polyvinyl chloride, polyethylene, polycarbonate, polypropylene, or polymethyl methacrylate.

It is composed of a small chamber larger is diameter than the tubing connecting it with the remainder of the administration system, or than the tubing connecting it to the supply container, so that the flow of fluid therethrough can be readily observed.

The twin valve T-connector 10 shown in FIGS. 3 and 4 has a coupling housing 55 that is molded in one piece entirely of plastic material, in this case, a modified phenylene oxide resin, sold commercially under the trade name Noryl. However, other thermoplastic or thermosetting moldable or castable plastic materials can be employed, such as ethyl cellulose, cellulose acetate-butyrate, cellulose propionate, nylon, polyphenylene oxide, polyethylene, polypropylene, polytetrafluoroethylene (Teflon), polychlorotrifluoroethylene (Kel-F), polystyrene, polyvinyl chloride, polycarbonates, polyoxymethylene (Delrin), epoxide resins, urea-formaldehyde, melamine-formaldehyde, phenol-formaldehyde, 2- methyl-pentene polymers (TPX), and polyester resins.

The coupling body constitutes a unit made in three pieces, the housing 55, and two fitting inserts 52 and 53, all of which, as shown in the Figures, are bonded together by softened integration of the plastic with a solvent, at their adjoining contacting surfaces. The coupling housing 55 as shown is in a T- shape, with three legs, 11, 14, 15, each of which bears a central passage 17, l8, 19, respectively, meeting at central chamber 54 of the housing. A T-shape has been adopted for convenience, but it will be evident that the configuration of the coupling is in no way critical. The three passage-bearing legs thereof can be set in the angles of a Y, or at any desired angle other than the angle shown in FIG. 3. The 90 angle is preferred, however, for reasons that will be apparent from the following discussion.

The central passages 17, 18 and 19 intersect at the center of the coupling housing. The coupling housing 55 at the outer end of the passage 17 has a reentrant portion 60 that defines a valve seat 61. Beyond the valve seat 61 is a wide bore 62 that extends to the exterior of the housing. A check valve 12 of the duckbill type is placed at the inner end of the bore 62 with the duckbill 68 facing inwardly from the valve seat 61, and with a base flange 66 abutting against the valve seat 61 in a leak'tight seal. The valve can be of any resilient or flexible heat-, water-, and solvent-resistant material, such as natural or synthetic rubber, for example, neoprene, or butadiene-styreneacrylonitrile polymer polypropylene, polyethylene, ethylenepropylene polymers, polyvinyl chloride or rubber hydrochloride resin. The base flange 66 of the valve is locked in position in the valve seat 61 by the fitting insert 52, which fits snugly in the bore 62 with its external wall bonded thereto by way of a solvent-formed bond.

The check valve 73 has the duckbill 68 enclosed snugly in a foam spring 13, which is of a resilient open cell foam sheet material, with through pores, such as foam rubber, styreneacrylonitrile rubber foam, polyethylene foam, polypropylene foam, silicone rubber foam, nylon foam, polyvinyl chloride foam, or polyether-based or polyester-based polyurethane foam. This spring tends to hold the duckbill closed snugly, and it can open only by a fluid pressure sufficient also to compress the sponge, thus providing a higher fluid opening pressure than would otherwise be the case, and aiding in preventing leakage from a supply bottle through the valve 73. The foam is highly porous, with through pores, of the order 0.005 to 0.025 inch in diameter, and even when compressed upon separation of the lips of the duckbill, fluid flow is permitted through the foam. The foam also serves as a filter, to a certain extent.

It will be appreciated that the fitting insert 52 can also be held in the bore 62 by a press fit, and it can also be bonded therein by a suitable binder. The sides of the bore can be threaded, and the fitting insert 52 correspondingly threaded, so that it can be screwed tightly into the bore, in which event the check valve 12 can be removed for replacement. In the preferred embodiment, however, the fitting 52 is permanently fixed in the bore 62. In all cases, the fitting holds the flange 66 of the valve 12 tightly against the valve seat 61 in a leak-tight seal.

It will be evident that the check valve 12 ensures that flow in the passage 17 is only in the direction shown by the arrow.

The fitting 52 has a central passage 67 connecting at its inner end with passage 78 through the check valve 12. In the bore ofa passage 67 is bonded the end oftubing 5.

At the inner end of the passage 19 in arm 15 the housing 55 is formed with a reentrant portion 70, defining at its inner end a valve seat 71, against which is seated a flange 72 of a check valve 73, also of the duckbill type. This check valve faces outwardly, so that flow in the passage 19 proceeds only in the direction shown by the arrow.

Beyond the valve seat 71, the housing 55 widens, and defines a bore 74 extending to the exterior of the housing 55. Held within the bore in a snug fit is the fitting insert 53, the inner end of which abuts against the exterior face of the flange 72 of the check valve 73, and holds it tightly in position against the valve seat 71, in a leaktight seal. The fitting insert 53 has an internal passage 77 through the check valve, and this passage receives the tubing 16, which is bonded therein.

The passage 18 does not contain a valve, and is adapted to receive in a press fit the delivery tip of the syringe 20 which pumps fluid through the T-connector. The syringe tip is shown in dashed lines in FIG. 3.

The operation of the T-connector of FIG. 3 is as follows. The delivery tip of a piston-type syringe 20 is pressed into passage 18 of arm 14. On the suction stroke the piston of the syringe on arm 14 draws fluid from the tubing via passages 78, 17 into the interior chamber 54 of the housing 55 into the syringe, and then on the pumping stroke the piston pumps this fluid through passages 18, 54, and 19 into and through the tubing 16. Thus, a volume of fluid is drawn. from the supply bottle equal to the capacity of the syringe attached to the arm 14, and then this volume is ejected via tubing 16 with each stroke on the piston. It will be evident that a lesser volume can be drawn, if desired, and that the volume is completely controllable by the user, according to the length of the stroke of the piston.

The device can similarly be used to withdraw fluid from a body cavity. In this event, the tubing 16 is attached to the fitting 52 of arm 11, and the tubing 5 attached to the fitting 53 of arm 15. Now, on the suction stroke, fluid is drawn out from the body cavity via tubing 16 and passages 17, 78, 54 and 18 and on the pumping stroke this fluid is pumped through passages 18, 54 and 19 into the tubing 5, and thence to the receiving bottle.

The device shown in FIGS. 3 and 4 is shown at four times its normal size. The actual capacity of the chamber 54, within check valve 73, externally of check valve 12, and externally of the syringe tip, including the volume of passages l7, l8 and 19, can be as little as 0.1 cc., or even smaller.

Any type of check valve can be employed. The duckbilltype of valve with duckbill tips shown in FIGS. 3 and 4 is preferred. There can also be employed poppet-type valves, ball-type valves, umbrella-type valves, and flap-type valves.

The foam spring is useful to hold any of these types of valves snugly closed and thus prevent leakage at all pressures below a predetermined minimum valve crack-open pressure. The spring is of resilient foam material and is interposed between the valve and the housing of the T-connector in such a position that the valve cannot open without compressing the foam spring. Preferably, the foam material is under some compression when the valve is closed, so that it aids in keeping the valve in a closed position, in the manner of a spring.

When the valve opens, it compresses the foam material, and at the same time fluid comes into contact with the material, and must pass through it to escape from the valve. The material thus acts against an open valve with even greater resistance than against a closed valve, and this aids in closing the valve to a tight snug seal as soon as fluid pressure is reduced to below the crack-open pressure.

The desired effect can be obtained by filling the fluid passage downstream of the valve with a foam plug, which is in close abutment to the valve on the side which moves outwardly in opening the valve. Thus, the plug can surround the jaws of a duckbill valve, or engage the downstream face of a flap or umbrella valve. If the plug is retained under compression in this position by some means in the passage, such as a constriction, or a flange, it will tend to hold the valve closed, and will be further compressed when the valve opens.

Other arrangements will be apparent. For instance, a sheet of foam material can be folded in a U or V over the jaws of a duckbill valve.

While the arrangements shown in the Figures of the valves in the arms and passages of the connectors are the preferred ones, so as to give the direction of flow shown, it will be apparent that the twin valves can be placed in any two of the arms, for any desired direction of flow. The arrangement shown prevents the entrapment of air in the chamber of the coupling, and it also prevents the kinking of flexible hose or tubing connected to the arms l1, 15.

A special feature of the T-connectors of the invention is that is it possible to draw fluid from any closed container without the need of venting the interior of the container, so as to relieve the vacuum that results. This is because of the extremely small internal volume of the T-connector. Due to the small internal volume (less than 1 cc. and preferably less than 0.1 cc.) a high compression ratio is obtained. The makes it possible to obtain pressures in a container of less than the vapor pressure of water and many other liquids. This means that no air need be introduced into a container to pump liquid out of the container.

In addition, it is possible to pump gases out of a container until extremely low pressures are reached. For example, with a valve having 0.1 cc. internal volume and a 50 cc. syringe, it is possible to pump a gas out of a container until a vacuum of 1/500 atmosphere is reached. Moreover, it is possible using a valve in accordance with this invention to pump gases with almost volumetric efficiency.

The construction of the T-connector is such that it possible to mold and cast it from any plastic that is thermoplastic or thermosetting but in a moldable or castable stage of polymerization. It can in fact be made easily in one unit from as few as five pieces, the coupling housing, the two valves, and two fitting inserts of valve insert pieces. If desired, the coupling housing also can be made in sagittal halves, and bonded together with the valves and socket adapters in place. The several parts can be permanently bonded together, by heat-sealing, integration of adjoining parts by fusing or solvent-bonding, or by an adhesive or bonding agent.

It may also be possible in some cases to mold the coupling housing in one piece, so that the valves can be inserted in their respective passages and sealed in place, with the ends of the passages being molded in the shape needed for reception of the desired types of connections. This reduces the total number of pieces to three; and eliminates the fitting insert pieces shown in the drawings.

The resulting device is simple, and easy to handle and clean. It is so inexpensive that it can be discarded after one use, for sanitary reasons. Since it can be entirely of heat-resistant and solvent-resistant material, it can be sterilized before use, and stored in a sterilizer for a considerable period of time, if desired, without deleterious effect.

It is possible to fabricate a coupling that is capable of withstanding the pressure necessary to pump from any type of container because the coupling can be formed by a molding or casting technique from nonresilient plastic materials with walls of a thickness to resist any fluid pressures that are likely to be encountered. In this respect, the nonresilient or rigid coupling of the invention is superior to couplings which have employed as a component of the construction a flexible tubing which incorporates the valves or connections to the pumping syringe or fluid supply.

The syringe pump in accordance with this invention shown in H0. comprises a Noryl base 8 housing a motor (not shown). The motor is operatively connected to an eccentric drive mechanism by a drive wheel 9, via a motor shaft 11. An eccentric drive pin 23 is located on the drive wheel 9. The drive pin is operatively connected to a pivoted yoke drive mechanism 24. The yoke comprises a pivoted bar 25 having a slotted portion at one end 26, for reception of the pin 23, and a lever portion 27, at the other end thereof. The drive pin 23 is located within the slotted portion 26 for pivotally moving the lever portion 27 upon rotation of the drive wheel 9. The lever portion 27 engages a plunger drive mechanism 28 for reciprocably moving a syringe plunger 22 within the syringe 20. The plunger drive mechanism 28 comprises a carriage 40 having a slotted portion 39 which engages the end 42 of plunger 22. The carriage is movable in the same direction as is the plunger in a slot (not shown) via a key 43. A set screw 44 is located adjacent to the lever portion 27 of the yoke drive 24 to limit the extent of the reciprocal motion of the plunger 29, upon pivotal motion of the yoke drive 24.

The syringe, which consists of a body portion 45, the plunger portion 22, a flanged end 46, and an aperture tip 47, is mounted on the housing with the plunger end 42 within the slotted portion of the plunger drive mechanism and the flanged end 46 within a pair of pincer snap clips 48. The pincer snap clips are composed of a rigid section 49a and a resilient arm member 49b. The resilient arm is made of spring steel and tightly holds the flange of the syringe in position as the plunger of the syringe is reciprocated within the body portion 45. The syringe iseasily demountable from the assembly by merely sliding it from the snap clips 49, and removing the plunger end 42 from the plunger drive mechanism 28.

The apertured tip of the plunger is attached to the leg 14 and passage 18 ofT-connector 10.

In operation, upon rotation of the motor shaft 11, the drive wheel 9 is rotated, thus causing eccentric motion of the pin 23. This pin moves the lever 27 of the yoke drive 24, thus causing reciprocal motion of the plunger within the body of the syringe. Fluid is pumped through the T-connector from the supply bottle 7 into tubing 16 in measured amounts, according lLL to the length of the stroke of the plunger and the capacity of the syringe body.

The syringe and T-connector can be readily removed from the pump assembly by merely withdrawing the syringe from the snap clips and the yoke and plunger drive mechanism, in the manner described.

The syringe used in the medicament administration system is an ordinary surgical syringe. Such syringes comprise a hollow cylinder having an apertured tip formed at one end and a laterally extending flange at the other end. The flange is normally provided as a convenient place for gripping the syringe when it is held in one hand. A plunger is provided for reciprocable movement within the cylindrical body. The plunger has an end which extends from the flanged end of the syringe. The plunger is fitted in a substantially fluidtight seal against the walls of the cylindrical body of the syringe and forms with the body a piston and cylinder pump. The seal on the plunger is normally maintained by a rubber seal. On the pumping or pressure stroke, the plunger pumps and so forces fluid from the syringe body through the tip, and on the suction stroke the plunger draws fluid into the body through the tip, for the next pumping or pressure stroke.

Surgical syringes are normally made from plastic material such as polyethylene or polypropylene; however, syringes made of any material that is inert to the fluid being pumped, such as glass, nylon, and Teflon, are suitable for use in this invention. The material is preferably transparent or translucent, but it need not be.

The syringe can be of generally any size, length and diameter, and of any capacity. Capacities from about 1 cc. to about 10 cc. are preferred for use in pumps of this invention.

The syringe is supported on a base which can normally also serve to house or support the drive means for the assembly. The case can be made from any material, such as wood, plastic, or metal. Plastic materials, such as nylon and polycarbonates, are preferred. The base can be formed in any desired or convenient shape, such as a cube.

One preferred syringe mounting member is a clamp of the snap clip type. The snap clips can be provided on the base in position to grasp the flanged portion of the syringe and, additionally, if desired, the cylindrical body of the syringe also.

The snap clips which engage the flanged portion of the syringe prevent any longitudinal displacement of the syringe which might occur when the plunger is reciprocated. Moreover, by providing clips which grasp the flanged portion guide firmly, it is possible to prevent any motion of the syringe at all. This makes it possible to employ only one set of clips which engage the flanged portion of the syringe to secure the syringe in position on the base.

If desired, an additional snap clip can be provided to engage and support the cylindrical body against any lateral displacement of the syringe which might otherwise occur.

Snap clips are preferred, since they are readily available and easily fabricated for special application. Moreover, they are long-wearing and simple to use. They permit easy insertion, removal and replacement of the syringe on the assembly, and can readily accommodate a wide range of syringes of different sizes, without any special adjustment.

A preferred snap clip for the flanged portion of the syringe comprises a pincer-shaped clip employing a rigid support member and a resilient pincer arm which bears against the support. The flange is inserted between the pincer arm and the support and is held in position therebetween by the spring force of the arm. This type of clip is preferred, since it has been found to provide firm support for the syringe on the base without any additional support members. It is adapted to readily accommodate syringes of different sizes since the size of the'flanged portion of the syringe does not vary greatly for different syringes. A clip of the type described above also permits easy insertion and removal of the syringe and accompanying administration system from the syringe pump assembly.

Snap clips are normally made at least in part of a highly resilient material, such as spring steel, or hard long-wearing resilient plastics, such as nylon or polypropylene.

Other suitable snap clips can be preferably C- or U-shaped depending upon the portion of the syringe they are to hold. For example, a snap clip that is positioned to hold the cylindrical body should be C" shaped and be oriented such that the body of the syringe is inserted into the open mouth of the C.

Another snap clip which can be used to engage the flanged portion of the plunger should be normally shaped as a narrow U" and be oriented such that the flange is inserted into the narrow open slot between the arms of the U.

It is also possible to provide snap clips which are of adjustable tension to ensure a tight grip on any size syringe used. Other mounting members for holding the syringe in place, such as clamps of all types, can be used. It is to be noted, however, that any mounting members provided should be readily adjustable and should be adapted to hold the syringe in a manner such that insertion and removal of the syringe from the assembly is readily accomplished.

The mounting members can be fixed in position on the base, and need not be movably mounted in order to hold different capacity syringes. This is due to the fact that the bodies of syringes of different capacities normally vary most in body diameter. This, however, does not affect the positioning of the mounting members, and thus they need not be movable on the base. However, if desired, the mounting members can be made adjustable on the base to occupy the same relative position for each different syringe.

The tip of the syringe communicates with the T-connector through which the fluid is pumped from the supply bottle to the air eliminator and thence the needle or other administration means.

The drive mechanism that is used in the instant pump assembly to reciprocate the plunger of the syringe is preferably an eccentric drive means that is powered by an electric motor. The motor can be housed in the base and be operatively connected to the eccentric drive member by a motor shaft. The eccentric drive member can be a cam, a Scotch yoke assembly, or the like. The drive mechanism, however, need not be an eccentric drive apparatus. Any mechanism adapted to convert the rotational motion of the motor to translational movement of the plunger of the syringe is suitable.

The drive mechanism should be disposed in a position such that rotation of the motor causes the drive mechanism to bear against the plunger of the syringe and cause reciprocal movement thereof.

If a cam drive is used, a spring can be employed as part of the drive mechanism to return the plunger to its original position, after the cam has forced the plunger to move inwardly. A compression spring disposed between the flanged portion of the cylindrical body and the end of the plunger is preferred.

The length of the movement of the plunger and the capacity and size of the syringe together determine the amount of fluid pumped on any one stroke. Means, such as stops, set screw, and lost motion linkages, can be provided to precisely control the length of the plunger movement.

The air eliminator 30 of FIGS. 6 and 7 comprises a rigid round transparent polymethyl methacrylate box housing 50 formed in three parts, an upper portion 51, a central annulus 56, and a lower portion 57, between which are fitted O-rings 58. These housing portions have thick wide walls, with four through bores 59, through which pass bolts 63, so that the three housing portions are held together in one piece.

Each housing portion is of a molded construction. Molded as an integral part of the central annulus 56 are the two fluid inlets 31, 33, and the lower portion is provided with a similar liquid outlet 36. For the same purpose, the top of the portion 51 is provided with port 32, which serves as an air gas vent, but two annular openings can also be provided. Tubing 16 is attached to inlet 31, air spring or cushion 34 to inlet 33, and tubing 37 to outlet 36.

. ill--.

A disk 64 of liquid-repellent or hydrophobic filter material, 0.1 micron average pore diameter, is held in the bite between the ledge 65 of the housing portion 56, and the perforated support member 69, made of polypropylene sheet, with l/ l 6 inch holes on 0.1 inch centers. A disk 76 of liquid-wetted or hydrophilic filter material is held in the bite between the ledge 65' of housing portion 56 and the perforated support member 75 of the same material as the member 69. The central housing portion 56 thus serves as a spacer ring, which fits between the portions 51 and 57 of the housing, supporting the liquid-repellent and liquid-wetted filter materials 64 and 76, and the span between ledges 65 and 65' thereof determines the width of the space or chamber 80 therebetween. This space can for instance be from 0.5 to 4.5 mm. The O-rings 58 assist in maintaining a liquid-tight seal between the filter materials and the housing portions 51, 56, 57. In like manner, the depth of the recess 81 in the housing portion 51 determines the width of the space or chamber 82 between the hydrophobic filter 64, and the top of the housing portion 51, and the depth of the recess 83 in the housing portion 57 determines the width of the space or chamber 84 between the hydrophilic filter 76 and the bottom of the housing portion 57.,

The liquid-repellent or hydrophobic filter 64 was prepared as follows:

A microporous filter material in sheet form was prepared, following the procedure of Example 1 of U.S. Pat. No. 3,353,682. The average pore size was 0.1 micron and the maximum pore less than 0.35 micron as determined by removal of the bacteria Serratia marcescens.

An aqueous fiber dispersion was prepared containing 5.4 g./l. of crocidolite type asbestos fibers having an average diameter of 0.5 micron and an average length of 300 microns and 0.6 g./1. of crocidolite fibers having an average diameter of 0.5 micron and an average length of 1,500 microns, by agitation in a high shear mixer having a rotor diameter of 7 inches, at a speed of 1,800 rpm.

An amyl acetate binder solution was prepared containing 4.75% by weight of neoprene, 0.2% by weight magnesium oxide and 0.24% by weight of zinc oxide, 0.05% by weight of tetraethylthiuram disulfide as a curing agent, 0.05% sodium dibutyl dithiocarbamate as a curing agent, 0.1 1% by weight of phenyl-beta-naphthylamine as a stabilizer, and 94.7% by weight amyl acetate.

This was blended into the fiber slurry at the region of highest shear in a ratio of neoprene to fibers of 15:100. Neoprene was deposited on the fibers, so that the fibers were coated with about 15% by weight neoprene.

A thin cellulose paper having a thickness of 0.0045 inch and a weight of 2.65 g./ft. was placed on the foraminous belt of a Fourdrinier machine, and served as the foraminous base sup port for laydown of the microporous material. The paper was used as the base rather than the mesh, to ensure a smooth-surfaced fine base layer. The paper was stripped from the microporous material after it had been laid down, and before curing.

The dispersion of fibers and binding agent was then flowed upon the paper support, and the resulting turbulence deflocculated some fibers, while some liquid drained out by gravity, thereby forming a thin first microporous layer of deflocculated fibers about 0.001 inch in thickness, of the mixed asbestos fibers, in which the fibers lay almost entirely in planes approximately parallel to the plane of the layer, and having an average pore diameter of 0.1 micron, and a maximum pore diameter of 0.35 micron. The flow through the support slowed as the layer formed, and the fibers in the supernatant liquid reflocculated. The belt was passed under a doctor blade which broke up excessively large flocs in the supernatant dispersion. Thereafter, a vacuum of 15 inches of mercury was applied on the underside of the foraminous belt, causing the supernatant dispersion to flow through the thin layer, depositing the remaining mixed asbestos fibers on the thin layer, under pressure flow, and forming a coarse layer having an average pore diameter of 0.25 micron, a maximum pore diameter of 0.55 micron and a thickness of about 0.004 inch.

The bilayered sheet so formed had a thickness (uncompressed) of 0.006 inch, and was dried under infrared lamps, and then oven-cured for 20 minutes at 310 F. It had a water permeability of gallons per minute per square foot at an applied pressure differential of 1S p.s.i. The voids volume of the relatively coarse layer was found to be about 84%, and for the thin layer, is was 60%.

This material was then treated with General Electric's RTV- l 12 silicone resin, to render it water-repellent. The treatment was carried out by impregnation using a 5% solution of RTV- l 12 silicone resin solution in perchloroethylene, followed by evaporation of the solvent, and curing the resin at 40% relative humidity and at 25 C. for 18 hours. The deposition rate was approximately 0.1 cc. of solution per square centimeter of filter material, extending to the opposite side of the material. The dry permeability of the material at 28 cu. ft. per minute of air per square foot was unchanged by the treatment.

The liquid-wetted or hydrophilic filter 76 was the same material, without the silicone resin treatment.

In use, medicament fluid containing both air and liquid enters via tubing 16 into the chamber 80 between the filter materials 64, 76. Fluid wets the hydrophilic liquid-wetted material 76, and as soon as the pores of this material are filled, air can no longer pass through. On the other hand, liquid does not wet the liquid-repellent material 64, and air is consequently free to pass through this material, reaching the chamber 82 on the other side thereof, and being vented to the atmosphere through the port 32. Liquid passing through the liquid-wetted material 76 enters the chamber 84, whence it is delivered from the device through the outlet 36 to tubing 37.

The fluid inlet 31 and liquid outlet 36 are shaped to match any type of fluid line in the system in which the air eliminator is to be used. The outlet 36 can also, for example, be adapted for connection directly to a Luer needle, instead of to a tubing leading to a Luer needle, as shown.

The air spring 34 is fed from chamber 80 via inlet 33. As a volume of fluid pulses through tubing 16 and reaches the chamber 80, fluid pressure increases in the chamber. This pressure is most easily relieved by the flow of fluid through inlet 33 into air spring 34, and this then follows, compressing the air therein. Such flow continues until the pressure of the air in the spring balances the fluid pressure, and then ceases. When the syringe pump enters the suction stroke, fluid pressure begins to fall, whereupon the pressure of air in the spring 34 eventually exceeds the fluid pressure, and fluid is forced out from the spring, back into chamber 80, via inlet 33. Now, fluid flow in line 16 has stopped and reverse flow is prevented by duckbill valve 73. Thus, such fluid passes through the filter 76 into chamber 84, and thence via outlet 36 to tubing 37. This tends to extend the period during which fluid flow proceeds in tubing 37 to the administration means. If the air spring 34 has a capacity to match the fluid volume delivered by the syringe in each pressure stroke in an appropriate proportional relationship that is readily ascertained in each system, a continuous flow in tubing 37 can be assured by the air spring 34.

The air eliminator of FIGS. 8 and 9 has a tubular housing 90 the open ends of which are closed off by flanged end caps 91, 92. The housing 90 is shown as closed, but it also can be perforated, to vent the air that is separated by the device to the atmosphere if desired. Each end cap has a recessed portion 93, at the center, engaging and centering within the housing a core tube 94 extending from end to end of the housing. This core limits the hold up volume in annular chamber 95, of which the core serves as the internal wall. At one end of chamber 95 is disposed outlet tube 96. The external wall of the chamber 95 is defined by a concentric stainless steel wire mesh tube 97, which also extends from end to end of the housing 90 and has its ends seated in the recessed grooves 98, in the end caps 91, 92, thus locating it concentrically with respect to the core. The mesh serves as a support for a corrugated hydrophilic or liquid-wetted tubular filter material 99. This material is of the membrane type, made of an acrylonitrile-vinyl chloride copolymer, cast on a nylon fabric support, and having a mean pore size of 0.45 micron and a thickness of 140 microns.

The filter 99 serves as the internal wall of an annular chamber 85, which is l to 25 mm. wide. At one end of chamber is a fluid inlet tube 86. The opposite wall of the chamber is defined by a corrugated tubular hydrophobic or liquid-repellent filter material which is supported on a perforated stainless steel tube 88. This material is also of the membrane type, with a polytetrafluorethylene membrane, mean pore size 0.5 micron, on a polyvinyl chloride fabric, and a thickness of 125 microns. The filter tube 87 and perforated tube 88 extend from end to end of the housing, and their ends are located in recessed grooves 89, in the end caps 91, 92, which space them con-centrically with respect to the other elements of the device. On the outer side of the tube 88 is an annular chamber 100, from one end of which leads the outlet tube 101.

The ends of the core 94, and tubes 97, 99, 87 and 88 are bonded to the inner face of the end caps 91, 92 by a layer of epoxy resin, forming a fluidtight seal there.

In use, medicament fluid containing air and liquid enters th device via inlet tube 86, entering the chamber 85. The liquid quickly wets and saturates the liquid-wetted filter 99, and from that time blocks the passage of gas therethrough. The liquid passing through the filter 99 and mesh tube 97 enters chamber 95, and leaves the device via outlet tube 96, free from air.

The hydrophobic or liquid-repellent filter material 87 blocks the entry of liquid, but is open to passage of air. Air passing through the filter 87 and tube 88 enters chamber 100, and leaves the device via outlet tube 101, free from liquid.

The air eliminator of FIGS. 10, 11 and 12 has a concave shape, to fit an arm or leg of the human body. The housing 1 10 is in two parts, 111, 112, with part 112 having a central recessed portion 113 in which a projecting portion 114 of part 111 nests. The two parts are solvent-fused together.

The recessed portion 113 of part 112 has a plurality of through holes 115 which serve as air vents, and in the recessed portion is disposed a hydrophobic filter material 116 of the type of FIGS. 6 and 7. This filter 116 is held at its periphery in the bite between housing parts 111, 112 and is solvent-bonded thereto in a leak-tight seal.

Housing part 111 has a bore 117 open to the exterior at 118 and serving as a liquid outlet, and a bore 119 open to the exterior at 120 and serving as a fluid inlet. A plurality of cross grooves 121 are provided at the inner face 122 of part 111 and intersect bore 117 at crossing points 123 for liquid flow via the grooves to the outlet 118. To the face 122 of the part 111 across the grooves 121 is bonded a hydrophilic filter material 124 of the type of FIGS. 6 and 7. This is done before assembly of part 111 to part 112. In the assembly, filters 116, 124 are parallel, and can be from 0.5 to 5 mm. apart, defining a chamber 125 therebetween, into which opens bore 119.

In use, medicament fluid containing air and liquid enters the separator at inlet 120, and flows through bore 119 into chamber 125. Liquid passes through hydrophilic filter 124, grooves 121, crossing points 123 into bore 117, and leaves the air eliminator at outlet 118. Air cannot pass through the filter 124, but it does pass through hydrophobic filter 116, which in turn blocks the liquid. Air enters the holes 115, and is vented thereby to the atmosphere.

This device can easily be strapped or otherwise attached to the limb of a patient for use in administration of some fluid medicament.

The air eliminator of FIGS. 13, 14 and 15 like that of FIGS. 6 and 7 is in disk form of transparent polymethyl methacrylate resin. There are three housing portions 130, 131, 132, the central portion 131 being merely an annulus. The three portions are solvent-bonded together to form an integral fluidtight housing. The inner face of portion is provided with a plurality of shallow parallel grooves 133, running lengthwise of the surface thereof, interconnected at the end with a circumferential groove 134 running only from the first to the last longitudinal groove 133 around the housing portion. The housing portion 132 is provided with a plurality of radial grooves 135 which intersect at the center 137 of the portion and circumferential concentric grooves 136 in a regular pattern. A plurality of segments 138 of the portion 132 are cut out, and serve as air vents over the grooves 136. Attached to the half 130 at the tops 140 of the raised portions between the longitudinal grooves 133 is a liquid-wetted filter material 143. This material is the same as that of FIGS. 6 and 7. Entering the housing portion 130 is a liquid outlet 139. The circumferential groove 134 connects the end of each of the longitudinal grooves 133 with the outlet 139. Thus, a fluid path is formed from the filter 143 via the grooves 133 into groove 134 leading to the fluid outlet 139. Attached to the inner face of housing portion 132, at the solid portion 149 between the grooves 135, 136, is a liquid-repellent filter material 150. This material is the same as that of FIGS. 6 and 7.

The housing 130 is provided with two inlets 141, 142, for attachment to a tubing, such as 16, and an air spring, such as 34. When annulus 131 is bonded in place to each of the housing portions 130, 132, the liquid-repellent filter material 150 is thereby held in a position spaced from and parallel to the liquid-wetted filter material 143, attached to the raised portions between crosswise grooves 135 of the housing portion 130, defining therebetween the chamber 148. The spacing between the filters 143, 150 can be for instance 0.5 to 2 mm. The chamber 148 thus defined has opposed parallel walls, made up of the liquid-repellent and liquid-wetted materials 143, 150. The inlets 141, 142 communicate with the chamber 148 between the two filter materials 143, 150.

In use, medicament fluid containing liquid and air enters the device via the fluid inlet 141, thus entering the chamber 148 between the liquid-repellent and liquid-wetted filter materials. The liquid quickly wets the liquid-wetted material 143, and after the pores therein are all filled, this material becomes impenetrable to air, while liquid passes freely therethrough, into the lengthwise grooves 133, and then into the circumferential groove 134, running therethrough to the liquid outlet 139, whence liquid is delivered from the device, quite free from air. Air which cannot pass through the liquid-wetted material 143 reaches the liquid-repellent material 150, passes through it into the grooves 135, 136 of the housing portion 132, and is vented thence via the segmental openings 138 at the atmosphere.

The air cushion 34 attached to inlet 142 functions in exactly the same manner as described in connection with FIGS. 6 and 7.

The air eliminators shown in the drawings as described above are useful to separate air from liquids in any type of medicinal and chemical application. They can, for instance, be used both to clear the medicament adminstration system line of air and to prevent the introduction of air into a patient receiving an injection of any type offluid medicament, such as a parenteral fluid, blood plasma, intravenous feeding solutions, needle-blockage-preventing flows, and the like. Such fluids can be delivered to a patient under high pressures, such as are encountered when the fluid delivery is effected by means of a syringe pump, and will prevent the introduction of air into the patient, at all pressures below the bubble point of the liquid-wetted filter material that is used, both at the beginning of the introduction of the liquid, even when the line before the separator contains air, and after delivery of fluid has exhausted the supply.

The air eliminator of the invention is quite versatile, and the construction design is such that it can be adapted to meet any air-liquid separation requirements. The essential materials of which it is constructed are known, and available, and readily lend themselves to the construction of devices of any desired size. For medical applications, it is usually preferable that the separator chamber between the two filter materials have as small a fluid volume as possible, less than 1 cc., and preferably less than 0.5 cc. The relative proportion of available surface area for the liquid-wetted and liquid-repellent materials can be adjusted as required, and will depend upon the relative volumes of fluid being processed, and of liquids and air being passed therethrough.

Because of the desirability of preventing distortion, and for greater strength and resistance to rupture, in most applications the housing is preferably of a rigid construction, using rigid sheets or molded or cast plastic parts, or metal, thus making it possible for the device to resist internal fluid pressures up to the bubble point of the filters used. If high fluid pressures are not to be encountered, however, the housing can be of a flexible construction, in which case it can be made of flexible sheet material, such as polyvinyl chloride, vinyl chloride-vinylidene chloride copolymers, polyesters, polyethylene or polypropylene sheet.

It is frequently helpful that the housing be transparent, so thatv the functioning of the device and the condition of the liquid-repellent and liquid-wetted filter materials can be observed, inasmuch as these materials also serve as filters, and will remove suspended solid material, such as dirt and other contaminants, which can lead to blockage.

Thus, for example, the housing can be constructed of rigid plastic material that is also transparent, such as polyethylene, polymethyl methacrylate, polycarbonates, polymethyl acrylate, polymethyl pentene-l, polyvinyl chloride, and vinyl chloride-vinylidene chloride copolymers. Translucent materials, such as polypropylene, polyethylene, urea-formaldehyde, and melamine-formaldehyde polymers, can also be employed. Other plastic materials that are particularly suitable are polystyrene, polyamides, polytetrafluorethylene, polyfluorotrichloroethylene, polyesters, phenol-formaldehyde resins, polyvinyl butyral, cellulose acetate, cellulose acetate propionate, ethyl cellulose and polyoxymethylene resins.

Metal housings can be used. Suitable metals include stainless steel, aluminum, and stainless alloys, such as nickel, chromium, vanadium, molybdenum, and manganese alloys. The housing material should, of course, be inert to the fluids being processed.

The filter materials, of which one is liquid-repellent and one is wetted preferentially by the liquid, can have any desired pore size according to the minimum bubble point required, according to the nature of the fluid being treated, and the nature of the contaminants, if any, to be removed. Since most filter materials are wetted by some liquids, and repel others, the materials chosen for each filter will depend upon the fluid being processed. If water is the liquid, then one of the filter materials is hydrophilic, and the other is hydrophobic.

In order to be effective in repelling and therefore not passing air, the liquid-wetted filter material should have a pore size of less than about 3 microns, and preferably less than 1 micron. In order to be effective in repelling and therefore not passing a liquid, the liquid-repellent filter material likewise should have a pore size of less than about 3 microns, and preferably less than about 1 micron. For bacteria removal purposes, as previously indicated, the pore size should be less than about 0.3 micron, and preferably less than 0.2 micron. A filter material that has too large a pore size can have the pore size reduced by impregnation, or coating, or both, with particulate and/or fibrous material. Such materials and procedures are known.

Thus, there can be used as the filter material woven or nonwoven textile materials made of cotton, jute, sisal, hemp, flax, linen, wood fiber, metal wire, such as stainless steel, copper and aluminum, plastic filaments (monofilaments and yarn) such as nylon, polyvinyl chloride, polyacrylonitrile, esters of terephthalic acid and ethylene glycol, cuprammonium rayon, acetate rayon, viscose rayon and polyvinylidene chloride; sintered composites made from metal powder or particles, such as stainless steel, copper, bronze, or monel, or from plastic particles, such as polyvinyl chloride, nylon, polyethylene, polypropylene, polytetrafluorethylene, and polyfluorotrichlorethylene; glass and ceramic materials; papers of various types, made up of cellulose fibers, cellulose cloth, plastic fibers, such as polyvinyl chloride, cellulose acetate, polyvinylidene chloride, nylon, and any of the other plastic filaments mentioned above, taken singly or in any combination; and microporous sheets, such as synthetic resin and cellulose derivative membrane filters.'

lmpregnated and/or coated microporous filter sheet materials meeting these general requirements and that in particular can be made with less than 0.3 micron pores and thus are useful for the removal of harmful micro-organisms include the microporous materials of US. Pat. Nos. 3,158,532 to Pall et al. dated Nov. 24, 1964, 3,238,056 to Pallet al. dated Mar. 1, 1966, 3,246,767 to Pall et al. dated Apr. 19, 1966, and 3,353,682 to Pall et al. dated Nov. 21, 1967. Also useful for this purpose are microporous ceramic filters and the microporous membrane filters described in US. Pat. Nos. 1,421,341 to Zsigmondy, 1,693,890 and 1,720,670 to Duclaux, 2,783,894 to Dovell, 2,864,777 to Robinson, and 2,944,017 to Cotton.

Liquid repellency is obtained, if the filter is of a material that is wetted by the liquid, by treatment with a material that repels the liquid when disposed on the surfaces of the pore walls of the filter material. The repellent material can be applied from a solution or dispersion thereof, in a solvent or dispersant which desirably includes a binder, to retain the repellent on the pore wall surfaces, unless the repellent is reactive therewith, and can bond itself thereto.

The application can be by printing, spraying, coating, impregnating, dipping, or by exposure to a vapor, such as that of a low boiling silicone compound. It is necessary to use a technique that results in thorough treatment of the entire length of the pores, from surface to surface of the filter material. This requires impregnation of the wall surfaces of the pores from end to end, best achieved by allowing the solution or dispersion of the repellent to flow into and through the pores in the treated zone, by capillarity or pressure application.

It will be appreciated that in nonwoven substrates, such as paper, nonwoven bats, and microporous layers formed by laydown from a fluid dispersion, the through pores that extend from one surface to another are composed of interconnected pores which are the interstices between the particulate material of which the material is made.

The amount of repellent that is required depends upon the effectiveness of the material as a repellent, and the volume of pores being treated. Usually less than 25% by weight of the volume being treated and preferably from 0.025% to by weight of the volume is sufficient.

The repellent is chosen according to the liquid suspending medium being filtered. It must repel such liquid, or be rendered so in situ on'the pore surface.

For a hydrophobic or water-repellent surface, there can be used silicone resins and silicone oils of the general type R,,-Si- O-Si-R,,, where n is l to 2. n is 1 in the case of the fluids, and n is 2 in the case of the solids, which contain cross-links between chains. Mixtures containing species in which n is from 1 to 3 can also be used. R is a hydrocarbon group having from one to 18 carbon atoms.

Also useful are the quaternary ammonium salt derivatives of silicone compounds described in US. Pat. No. 2,738,290, dated Mar. 13, 1956. These are substantive to cellulosic filter materials, as noted in the patent. Also, the hydrophobic oils and waxes can be used, in appropriate circumstances, where they can be made permanent.

If the filter material is liquid-repellent, and it is desired to make it liquid-wetting, itis advantageous to apply a liquidwetted material thereto. The same treatment principles and proportions apply to liquid-wetted materials as to liquid-repellent materials, but the proportions are less, of the order of 0.1% of the wetting agent, or less. Typical wetting agents that are suitable are polyvinyl alcohol, alkyl aryl polyether alcohols, melamine-formaldehyde resins, sodium lauryl sulfate, and the like. These wetting agents can be applied from a solution.

Some liquid-repellent materials can also be made liquidwetted temporarily by adding a solution of the liquid containing 0.5% or less of a wetting agent. The wetting agent will make it possible for the liquid to wet, impregnate and saturate the material quickly with the liquid, which will then stay there until the material is dried out, and throughout the intervening period, the material will behave as though it were really liquidwetted.

The filter material that is liquid-repellent and therefore passes the air being separated from the liquid is so placed in the housing that the air can reach it and pass through it to the air outlet in the housing. Inasmuch as air normally rises, this means that at least a part of the liquid-repellent filter preferably is at an upper portion or wall of the chamber in the housing. If the liquid-repellent filter is confined to a lower portion of the housing, the air may not pass through it until an air pocket deep enough to reach the uppermost portion of the liquid-repellent filter has built up in the chamber. The building up of such an air pocket is not a disadvantage, if the liquidwetted filter material is still fully open to the passage of fluid, and is not covered by or immersed in the air pocket, but such a device may be position-sensitive. It is therefore less preferred, for some uses.

For convenience of construction and minimum volume, in the air eliminator of the invention the liquid repellent and liquid-wetted filter materials are substantially parallel, are as close together as is practical and still define a space therebetween that is open to the air-liquid mixture to be separated, and define opposed parallel walls of the housing chamber. A suitable spacing of the filters is from 0.25 mm. to about 5 mm., for medicinal uses, as an air separator in a supply line to a patient. For other purposes, there is no limit except that dictated by the dimensions and flow requirements of the system in which it is to be placed.

In the simplest construction, the separator walls are straight, as well as parallel. However, in this case the liquid-repellent wall normally must be uppermost, if air blockage is to be avoided.

Another type of construction, which avoids the possibility of air blockage in the chamber, regardless of the position of the device, has the liquid-repellent and liquid-wetted separator walls arranged in parallel in a U configuration, with the air being vented either on the exterior or the interior walls of the U. In either case, regardless of the position of the device, a portion of the liquid-repellent wall is always uppermost in the device, so that air can reach it and thus be vented, even if other portions of the same liquid-repellent wall be immersed in liquid.

It is also possible to arrange the liquid-repellent and liquidwetted walls in an N, a V or even a W configuration, with similar results. One of the filter materials can cross the chamber diagonally or at an angle to the other filter material comprising another wall thereof, and can if desired contact the latter at one end in an S or Z configuration.

The liquidrepellent and/or liquid-wetted materials can also be arranged in a corrugated or undulating configuration, or in a raised, waffled or dimpled pattern for a greater surface area in a small space. In this case, the surface of the filters is uneven, so that air blockage due to air pockets is unlikely, since the air will not be in contact with all portions of the filter. 1f the raised portions of either the liquid-repellent or the liquid-wetted filter material are virtually in contact with the other, the depressed portions then provide space for passage of liquid therebetween, while the close spacing of the abutting raised portions ensures that air can reach and escape through the liquid-repellent filter, whatever the position of the device. Thus, this also avoids positiomsensitivity, as do the N, S, U, V, W and Z configurations.

For simplicity of construction, the housing is best formed in two or three matching pieces, which when assembled define the separator chamber therebetween, with the liquid-repellent filter material fixed in one portion of the housing, and the liquid-wetted filter material fixed in the other portion of the housing, at opposite sides of the chamber, and preferably parallel or nearly parallel to each other in the final assembly.

These parts can be separately molded, and then attached together, by bolts, or by heat-fusing, or by solventor adhesive-bonding. In the case of plastic materials, solvent-bonding is a preferred attachment technique, because it eliminates the presence of extraneous adhesives, does not affect transparency at the joints of a transparent housing, and is also leakproof.

The housing parts are constructed so that the filter materials contained therein are spaced from the outer walls thereof, and define spaces therebetween. The housing part containing the liquid-repellent material has an air outlet or vent communicating with the space on the outside of the liquid-repellent material, and the housing part containing the liquid-wetted material has a liquid outlet or vent communicating with the space on the outside of the liquid-wetted material. The housing thus has at least three chambers, the intermediate chamber being that to which the fluid containing both air and liquid is delivered for separation of the air therefrom, and two outer chambers on opposite sides of the liquid-repellent and liquidwetted materials, respectively, being adapted to vent air separated from the liquid, and to deliver liquid from which air has been separated.

The limiting fluid pressure at which a liquid repellent filter material will no longer resist passage of fluid therethrough is readily determined, just as is the limiting pressure beyond which a filter wetted by a liquid will pass a gas. Both limits are significant in the air eliminators of the invention, the first because it is the limiting pressure at which the air eliminator begins to leak fluid through the air vent, and the second because it is the pressure at which the system will begin to leak air into a patient. Neither limit can be exceeded, therefore.

It is relatively easy to select a liquid-wetted filter material having a high enough bubble point to resist passage of air at all fluid pressures that might conceivably be encountered. However, it is more difficult to select a liquid-repellent material that will resist passage of fluid at fluid pressures at which the liquid-wetted filter material easily resists passage of air. The invention accordingly provides a way around this difficulty, in the form of an air spring or cushion that reduces the peak pressure in the system, that is reached in the course of the pumping stroke ofthe syringe plunger.

The air spring or cushion is a dead end air chamber on the upstream side of the air eliminator, usually connected to the flow chamber on that side. When a pressure surge reaches the spring, the surge is at least partially absorbed by flow of fluid into the air spring, compressing the air normally contained therein, and correspondingly reducing fluid pressure on the upstream side of the liquid-wetted and liquid-repellent filters. This pressure reduction greatly improves the likelihood of preventing leakage of either air or liquid past the wrong filter at this pressure surge. Then, on the suction stroke of the syringe plunger, the pressure is reduce, and the compressed air in the spring forces the fluid out again. This not only tends to equalize fluid pressure differences between the pressure and suction strokes of the plunger, but also promotes a more uniform flow of fluid to the patient.

It is possible to design the air spring so that a steady flow of fluid is supplied at the administration means of the system. This flow will necessarily be at a slower rate than the rate of flow delivered by the syringe on the pressure stroke, but it will be continuous, and at a relatively uniform pressure. All that needs be done is adjust the capacity of the air cushion or spring to equal the volume of fluid delivered per stroke, and appropriately adjust the flow delivery capacity of the administration means so as to deliver this volume of fluid only in the time required for the syringe pump to complete a cycle of one pressure and one suction stroke. In a typical system, this can be virtually ensured at any needle size offering a flow resistance of at least lbs./sq.in.

The air cushion is normally dimensioned so as to reduce the peak fluid pressure at the air eliminator to no more than 25% above the normal peak pressure on the pressure stroke. This is a significant reduction, since the peak pressure can be as much as six times higher, or more. If the volume of the air spring is equal to the volume of fluid delivered per stroke of the syringe, the peak pressure is reduced by 50%. Each doubling of the volume gives a further reduction of 50%. Since pressure is reduced, flow rate is also correspondingly reduced.

The air spring or cushion can take the form of a fluidtight chamber or pocket of any suitable dimensions, according to the volumes of fluid delivered per stroke of the syringe plunger, and the frequency of the strokes. The damping action can be complemented by appropriate dimensioning of the inlet and outlet access openings or passages leading to the pressure chamber.

The chamber walls can be resilient, aiding the damping action. The use of resilient flexible tubing is particularly advantageous.

The air spring pressure chamber walls can be transparent or translucent, so the point of advance of the fluid therein can be observed by locating the meniscus. Since the fluid pressure is a function of the advance of fluid into the chamber, against the air pressure therein, the walls can be marked in a scale, from which pressure can be read off directly, after calibration against a pressure gauge. In this event, the spring chamber is preferably in the form of a narrow tube, with rigid or relatively nondistensible walls.

The administration system of FIG. 16 like that of FIGS. 1 and 2 comprises a visual flow indicator 1, made of transparent flexible plastic, such as polyvinyl chloride, in tubular form, with the ends 2, 3 pinched and permanently heat-sealed to a tube connector 4 for attachment to a supply bottle, and to a flexible tubing 5 which connects with a T-connector 10. The details of the T-connector are shown in FIGS. 3 to 4. The tubing 5 is bonded in a leak-proof seal to the leg 1 l of the T-connector, in which is disposed a check valve 12, in this case, a duck bill valve, which ensures that flow isonly in one direction, towards the T-junction chamber 54 in the T-connector. One of the other legs 14 of the T-connector is adapted to be attached to a syringe 20', which is in turn adapted for insertion in a syringe pump 21, as is more particularly shown in FIG. 5.

The third leg 15 of the T-connector is attached to a tubing 16, which is bonded thereto in a leak-proof seal. The tubing runs to the inlet 31 of an air eliminator 30, from which air is vented via the port 32. The details of the air eliminator are shown in FIGS. 6 and 7.

Attached to an inlet 33 of the air eliminator is an air spring or cushion 34, in the form of a dead end piece of flexible tubing, filled with air. As the syringe pump advances on its pressure stroke, with pumping movement of the plunger 22 of the syringe 20, a pulse of fluid pressure advances through the system, and its presence is indicated by an advance of fluid in the air spring 34, compressing the air in the spring. The degree of compression is proportional to the fluid pressure, and therefore the spring 34 can also serve as a pressure gauge, from which the pressure can be read off by appropriate gradations 35 of a pressure scale marked on the spring 34. This spring has the function of taking up the pressure surge, and equalizing pressure to some degree beyond the air eliminator 30. If the flow through the needle is low, the spring can even ensure a steady fluid flow through the needle, evening out the pressure surges in fluid flow from the syringe pump.

In operation, the tube connector 4 is attached to the stopper 6 of a supply bottle 7, as shown in FIG. 2, and the syringe 20 is attached to the leg 14 of the T-connector, and then is fitted in the cradle of a syringe pump. The needle 41 is at this point unattached. The pump is started, whereupon fluid is pumped from the supply bottle 7 through the tubing 6, connector 4, visual flow indicator 1, tubing 5, T-connector 10, syringe 20', tubing 16, air eliminator 30, tubing 37, needle adapter 38 and needle 41, clearing air from the system. The needle is then inserted in the patient, and administration begun.

As the syringe pump delivers a volume of fluid via the T- connector through tubing 16, a comparable volume of fluid enters the air spring 34, compressing the air in the air spring,

while fluid flow proceeds via the air eliminator at a reduced pressure through tubing 37 to the needle. The syringe pump on its suction stroke draws fluid from the supply bottle 7, and flow in tubing 16 ceases, whereupon fluid pressure drops. The compressed air in air spring 34 now exceeds fluid pressure in the air eliminator 30 and beyond, and forces fluid in the air spring into the air eliminator 30. Since the twin valve T-connector prevents reverse flow in tubing 16, fluid flow continues in tubing 37 to the needle, now under the pressure of the compressed air in the air spring. If the volume of the air spring is sufficient, this flow can continue until the syringe pump has ended its suction stroke and begun its pressure stroke, so that a steady flow of fluid at the needle is obtained.

The visual flow indicator 1 is of conventional construction, and any type of such indicator can be used. It is preferably made of transparent material, although translucent materials can also be employed, and is best made of plastic or glass, such as polyvinyl chloride, polyethylene polycarbonate, polypropylene, or polymethyl methacrylate.

It is composed of a small chamber larger in diameter than the tubing connecting it with the remainder of the administration system, or than the tubing connecting it to the supply container, so that the flow of fluid therethrough can be readily observed.

The administration system of the invention is suitable for administration of fluid medicaments of all types, including plasma nutrient solutions, vitamins, and drugs, such as antibiotics, narcotics, parenteral fluid, for intravenous, subcutaneous or intra-peritoneal injection, or for oral, vaginal or rectal administration. It is easily and quickly attached to standard administrative supply containers, and administration kits, such as needles, nipplies, and spouts. Since it is composed of permanently assembled parts, it is sterilizable as a unit, before use, and is thrown away as a unit, after use. The parts although new are inexpensive, and due to savings in labor and the ease and safety of handling, it is less expensive to use than most systems now in use, made up of various combinations of disposable parts and of parts that must be re-used, after resterilization.

Having regard to the foregoing disclosure, the following is claimed as the inventive and patentable embodiments thereof:

1. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and a syringe pump, and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve T- connector for attachment to a supply reservoir; an air eliminator comprising a housing having liquid-and gas-impervious exterior walls defining a chamber within the housing, of which chamber a first wall comprises a first filter material that is wetted by a liquid to be passed through the housing but when so wetted will not pass a gas, and a second wall opposite the first comprises a second filter material that is not wetted by the liquid but will pass a gas entering the chamber, said second filter material being sufficiently closely spaced from the first filter material that gas will reach and pass through the second filter material in any position of the separator, an inlet in the housing for delivering to the chamber between the two opposite filter materials a fluid comprising a gas and liquid, a liquid outlet in the housing on the other side of the first wall of the chamber, so that liquid entering the chamber must pass through the first filter to reach a liquid outlet, and a gas outlet in the housing on the other side of the second wall of the chamber, so that all gas entering the chamber must pass through the second filter material to reach the gas outlet; and a delivery means; all interconnected by fluid delivery tubing, in an airand liquid-tight manner.

2. A disposable fluid administration system in accordance with claim 1, wherein the liquid-wetted and the liquid-repellent materials of the air eliminator have an average pore size less than about 0.3 micron.

3. A disposable fluid administration system in accordance with claim 1, wherein the housing and associated parts of the air eliminator are made of plastic.

4. A disposable fluid administration system in accordance with claim 1, in which the liquid-wetted and liquid-repellent filter materials of the air eliminator are at opposite sides of the chamber.

5. A disposable fluid administration system in accordance with claim 1, wherein the space between the liquid-wetted and liquid-repellent walls is less than 5 mm.

6. A disposable fluid administration system in accordance with claim 1, wherein the filter materials are each microporous.

7. A disposable fluid administration system in accordance with claim 1, in which the air eliminator housing is in three parts, comprising an annulus defining the chamber walls between the liquid-wetted and liquid-repellent filter materials, and having the fluid inlet in one wall thereof, the annulus being intermediate and attached in a fluid tight seal to two outer portions, in one of which is disposed the gas outlet, the liquid-repellent filter material being disposed across the line of flow between the chamber and the gas outlet, and in the other of which is disposed the liquid outlet, the liquid-wetted'material being disposed across the line of flow between the chamber and the liquid outlet, so that all fluid entering the chamber must pass through one of the filter materials to reach an outlet.

8. A disposable fluid administration system in accordance with claim 1, in which the air eliminator housing is in two parts, in one of which is disposed the liquid-repellent filter material, across the line of flow between the chamber and the gas outlet, and in the other of which is disposed the liquidwetted filter, across the line of flow between the chamber and the liquid outlet, so that all fluid entering the chamber must pass through one of the filter materials to reach an outlet.

9. A disposable fluid administration system in accordance with claim 1, wherein the housing has at least one surface facing the filter material that is channeled for fluid flow towards the outlet from the filter material.

10. A disposable fluid administration system in accordance with claim 9 wherein the channels are in the form of an intersecting grid of grooves extending generally crosswise and generally lengthwise of the housing portion.

11. A sterile disposable administration system in accordance with claim 1 that is especially designed for use with a syringe pump and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve T- connector for attachment to a supply reservoir, a syringe having a plunger adapted to be reciprocated by a pump drive, an air eliminator, and a delivery means, all interconnected by fluid delivery tubing, in an airand liquid-tight manner.

12. A disposable fluid administration system in accordance with claim 11 comprising an air spring associated with and on the upstream side of the air eliminator.

13. A disposable fluid administration system in accordance with claim 1 comprising a visual flow indicator on the upstream side of the T-connector.

14. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient comprising, in combination and in series, a twin valve T-connector for attachment to a supply reservoir; an air eliminator; an air spring associated with and on the upstream side of the air eliminator; and a delivery means; all interconnected by fluid delivery tubing, in an airand liquid-tight manner.

15. A disposable fluid administration system in accordance with claim 14, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by pumping action of the syringe.

16. A disposable fluid administration system in accordance with claim 15 wherein the chamber walls are of transparent or translucent material.

17. A disposable fluid administration system in accordance with claim 16 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.

18. A disposable fluid administration system in accordance with claim 2, including a syringe attached to the T-connector.

19. A disposable fluid administration system in accordance with claim 14, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by pumping action of the syrmge.

20. A disposable fluid administration system in accordance with claim 19, wherein the chamber walls are of transparent or translucent material.

21. A disposable fluid administration system in accordance with claim 20, wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.

22. A disposable fluid administration system in accordance with claim 14, comprising a visual flow indicator on the upstream side of the T-connector.

23. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient comprising, in combination and in series, a twin valve-T-connector for attachment to a supply reservoir having a coupling body (formed) of plastic material (and as one unit) having three interconnected passages therethrough, check valves in two of said passages controlling flow of fluid therethrough in a single direction; the check valve in at least one of said passages having retaining means at an outer peripheral portion thereof, a fitting insert in each valve-containing passage, comprising a plastic material which is either the same as or compatible with the plastic material of the coupling body, the fitting insert extending into the said passage from the outside of the coupling body, and having a central passage therethrough for passage of fluid into and out from the T-connector, said valve-retaining means being retained by the fitting insert against the coupling body and a peripheral portion of the fitting insert closely abutting an inner wall of the passage, and being integrated with the plastic material of the coupling body, obliterating any seam therebetween at that portion, and forming a leaktight barrier, the fitting insert thus retaining the valve in the coupling body in a permanent leaktight fit; the other check valve being fixed in the other passage in a leaktight seal between the retaining means and either the coupling body of a like insert; the passage that does not include a check valve being adapted to be attached to a syringe having a plunger adapted to be reciprocated by a pump drive; an air eliminator attached to one of the passages including a check valve, the two check valves together controlling flow of fluid through the system in a direction from the syringe on the pumping stroke of the plunger, towards the air eliminator; and a delivery means on the downstream side of the air eliminator; all interconnected by fluid delivery tubing in an airand liquid-tight manner.

24. A disposable fluid administration system in accordance with claim 23, wherein the coupling body is made of plastic in a T-configuration in one piece, and the passages are interconnected at a central portion of the body. (the twin valve T-connector comprises a coupling housing having in at least one valve-containing passage a fitting retaining the valve in the passage and having a passage therethrough connecting with the coupling housing passage at the inner end and the connection means at the outer end.)

25. A disposable fluid administration system in accordance with claim 24, wherein both the coupling body and inserts are formed of the same plastic material. (the fittings are secured to the coupling housing and the coupling housing is in one piece.)

26. A disposable fluid administration system in accordance with claim 23, in which the twin valves are duckbill valves.

27. A disposable fluid administration system in accordance with claim 23, in which the passage for delivery of fluid is in alignment with the passage to which the syringe is attached. and the passage connected to the fluid supply is at right angles to said passage.

28. A disposable fluid administration system in accordance with claim 23, in which the interior volume of the coupling body between the valves is less than 1 cc.

29. A disposable fluid administration system in accordance with claim 23, in which the coupling body is formed of molded plastic.

30. A disposable fluid administration system in accordance with claim 23, in which the coupling body is made of a relatively rigid plastic.

31. A disposable fluid administration system in accordance with claim 23, in which the check valve is associated with a resilient foam spring to ensure a leak-tight seal when the valve is closed.

32. A disposable fluid administration system in accordance with claim 23, including a syringe attached to the T-connec-v tor.

33. A disposable fluid administration system in accordance with claim 23, including an air spring associated with and on the upstream side of the air eliminator.

34. A disposable fluid administration system in accordance with claim 33, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by pumping action of the syringe.

35. A disposable fluid administration system in accordance with claim 34 wherein the chamber walls are of transparent or translucent material.

36. A disposable fluid administration system in accordance with claim 34 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.

37. A disposable fluid administration system in accordance with claim 23 comprising a visual flow indicator on the upstream side of the T-connector.

38. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve T-connector having a coupling body of plastic material having three interconnected passages therein; check valves in two of said passages controlling flow of fluid therethrough in a single direction, said check valves each comprising a valve member of rubbery material having retaining means thereon held in a fixed position in its passage in a leaktight seal and moveable in a flex action movement at a peripheral portion thereof to engage a valve seat or like valve member in a relatively leaktight seal so as to close the passage and to crack open in a flex action movement with respect to the fixed portion away from the valve seat or like valve member, said valve member presenting a surface exposed and responsive to fluid pressure on each side thereof and being responsive to a fluid pressure on one side tending to bias the valve member against the valve seat or like valve member in a leaktight seal therewith and thus prevent flow from that side, and being responsive to fluid pressure on the other side to move away from the valve seat or like valve member and thus permit flow from that side at the crack-open pressure and thereafter; a fitting insert in each valve-containing passage of a plastic material which is the same as or compatible with the plastic material of the coupling body, the fitting insert extending into the said passage from the outside of the coupling body, and having a central passage therethrough for passage of fluid into and out from the T-connector, each fitting insert engaging the valve in its passage so as to capture the retaining means on the valve between the body and the insert, and having a peripheral sidewall abutting the sidewalls of the passage and being bonded with the material of the coupling body forming a leaktight barrier, the fitting insert thus retaining the valve in the coupling body in a permanent leaktight fit, the passage that does not include a check valve being adapted to be attached to a syringe having a plunger adapted to be reciprocated by a pump drive, an air eliminator attached to one of the passages including a check valve, the two check valves together controlling flow of fluids through the system in a direction from the syringe on the pumping stroke of the plunger towards the air eliminator and a delivery means on the downstream side of the air eliminator, all interconnected by fluid delivery tubing in an airand liquid-tight manner.

39. A disposable fluid administration system in accordance with claim 38 including a syringe attached to the T-connector.

40. A disposable fluid administration system in accordance with claim 38 including an air spring associated with and on the upstream side of the air eliminator.

41. A disposable fluid administration system in accordance with claim 40 wherein the air spring comprises a chamber and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by the pumping action of the syringe.

42. A disposable fluid administration system in accordance with claim 40 wherein the chamber walls are of transparent or translucent material.

43. A disposable fluid administration system in accordance with claim 41 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.

44. A disposable fluid administration system in accordance with claim 42 comprising a visual flow indicator on the upstream side of the T-connector.

2-147 CIP P0405) UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent: No. 3 650L093 Dated March 21, 1972 Inventor( Jo R0senberg It is certified that error appears in the above-identified petent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 72 A: "no" should be not Column 3, line 6 'for" should be to Colllmn 3, line 29 Alf-tel". "is", irlsert in Column 4, line 40. After "mime 11 delete Columrll, llnegi "he should be the Column 4, line 53 After "the", insert "liquid-Velma and delete "micro-organisms" Column 4, line 54 Delete "the"; SeCOnd rr nce,

l'msert on- Column 8, line a T "The" sho u1dbe This Column 9, 11% 1 After it", insert f-- is Column l2,-'line 34 I "g./1." should be g./l. Column 13, line 7 T :I, 'is" should be it a. v Y 

1. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and a syringe pump, and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve Tconnector for attachment to a supply reservoir; an air eliminator comprising a housing having liquid-and gas-impervious exterior walls defining a chamber within the housing, of which chamber a first wall comprises a first filter material that is wetted by a liquid to be passed through the housing but when so wetted will not pass a gas, and a second wall opposite the first comprises a second filter material that is not wetted by the liquid but will pass a gas entering the chamber, said second filter material being sufficiently closely spaced from the first filter material that gas will reach and pass through the second filter material in any position of the separator, an inlet in the housing for delivering to the chamber between the two opposite filter materials a fluid comprising a gas and liquid, a liquid outlet in the housing on the other side of the first wall of the chamber, so that liquid entering the chamber must pass through the first filter to reach a liquid outlet, and a gas outlet in the housing on the other side of the second wall of the chamber, so that all gas entering the chamber must pass through the second filter material to reach the gas outlet; and a delivery means; all interconnected by fluid delivery tubing, in an air- and liquidtight manner.
 2. A disposable fluid administration system in accordance with claim 1, wherein the liquid-wetted and the liquid-repellent materIals of the air eliminator have an average pore size less than about 0.3 micron.
 3. A disposable fluid administration system in accordance with claim 1, wherein the housing and associated parts of the air eliminator are made of plastic.
 4. A disposable fluid administration system in accordance with claim 1, in which the liquid-wetted and liquid-repellent filter materials of the air eliminator are at opposite sides of the chamber.
 5. A disposable fluid administration system in accordance with claim 1, wherein the space between the liquid-wetted and liquid-repellent walls is less than 5 mm.
 6. A disposable fluid administration system in accordance with claim 1, wherein the filter materials are each microporous.
 7. A disposable fluid administration system in accordance with claim 1, in which the air eliminator housing is in three parts, comprising an annulus defining the chamber walls between the liquid-wetted and liquid-repellent filter materials, and having the fluid inlet in one wall thereof, the annulus being intermediate and attached in a fluid tight seal to two outer portions, in one of which is disposed the gas outlet, the liquid-repellent filter material being disposed across the line of flow between the chamber and the gas outlet, and in the other of which is disposed the liquid outlet, the liquid-wetted material being disposed across the line of flow between the chamber and the liquid outlet, so that all fluid entering the chamber must pass through one of the filter materials to reach an outlet.
 8. A disposable fluid administration system in accordance with claim 1, in which the air eliminator housing is in two parts, in one of which is disposed the liquid-repellent filter material, across the line of flow between the chamber and the gas outlet, and in the other of which is disposed the liquid-wetted filter, across the line of flow between the chamber and the liquid outlet, so that all fluid entering the chamber must pass through one of the filter materials to reach an outlet.
 9. A disposable fluid administration system in accordance with claim 1, wherein the housing has at least one surface facing the filter material that is channeled for fluid flow towards the outlet from the filter material.
 10. A disposable fluid administration system in accordance with claim 9 wherein the channels are in the form of an intersecting grid of grooves extending generally crosswise and generally lengthwise of the housing portion.
 11. A sterile disposable administration system in accordance with claim 1 that is especially designed for use with a syringe pump and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve T-connector for attachment to a supply reservoir, a syringe having a plunger adapted to be reciprocated by a pump drive, an air eliminator, and a delivery means, all interconnected by fluid delivery tubing, in an air- and liquid-tight manner.
 12. A disposable fluid administration system in accordance with claim 11 comprising an air spring associated with and on the upstream side of the air eliminator.
 13. A disposable fluid administration system in accordance with claim 1 comprising a visual flow indicator on the upstream side of the T-connector.
 14. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient comprising, in combination and in series, a twin valve T-connector for attachment to a supply reservoir; an air eliminator; an air spring associated with and on the upstream side of the air eliminator; and a delivery means; all interconnected by fluid delivery tubing, in an air- and liquid-tight manner.
 15. A disposable fluid administration system in accordance with claim 14, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned To absorb at least in part pressure surges created by pumping action of the syringe.
 16. A disposable fluid administration system in accordance with claim 15 wherein the chamber walls are of transparent or translucent material.
 17. A disposable fluid administration system in accordance with claim 16 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.
 18. A disposable fluid administration system in accordance with claim 2, including a syringe attached to the T-connector.
 19. A disposable fluid administration system in accordance with claim 14, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by pumping action of the syringe.
 20. A disposable fluid administration system in accordance with claim 19, wherein the chamber walls are of transparent or translucent material.
 21. A disposable fluid administration system in accordance with claim 20, wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.
 22. A disposable fluid administration system in accordance with claim 14, comprising a visual flow indicator on the upstream side of the T-connector.
 23. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient comprising, in combination and in series, a twin valve-T-connector for attachment to a supply reservoir having a coupling body (formed) of plastic material (and as one unit) having three interconnected passages therethrough, check valves in two of said passages controlling flow of fluid therethrough in a single direction; the check valve in at least one of said passages having retaining means at an outer peripheral portion thereof, a fitting insert in each valve-containing passage, comprising a plastic material which is either the same as or compatible with the plastic material of the coupling body, the fitting insert extending into the said passage from the outside of the coupling body, and having a central passage therethrough for passage of fluid into and out from the T-connector, said valve-retaining means being retained by the fitting insert against the coupling body and a peripheral portion of the fitting insert closely abutting an inner wall of the passage, and being integrated with the plastic material of the coupling body, obliterating any seam therebetween at that portion, and forming a leaktight barrier, the fitting insert thus retaining the valve in the coupling body in a permanent leaktight fit; the other check valve being fixed in the other passage in a leaktight seal between the retaining means and either the coupling body of a like insert; the passage that does not include a check valve being adapted to be attached to a syringe having a plunger adapted to be reciprocated by a pump drive; an air eliminator attached to one of the passages including a check valve, the two check valves together controlling flow of fluid through the system in a direction from the syringe on the pumping stroke of the plunger, towards the air eliminator; and a delivery means on the downstream side of the air eliminator; all interconnected by fluid delivery tubing in an air- and liquid-tight manner.
 24. A disposable fluid administration system in accordance with claim 23, wherein the coupling body is made of plastic in a T-configuration in one piece, and the passages are interconnected at a central portion of the body. (the twin valve T-connector comprises a coupling housing having in at least one valve-containing passage a fitting retaining the valve in the passage and having a passage therethrough connecting with the coupling housing passage at the inner end and the connection means at the outer end.)
 25. A dispOsable fluid administration system in accordance with claim 24, wherein both the coupling body and inserts are formed of the same plastic material. (the fittings are secured to the coupling housing and the coupling housing is in one piece.)
 26. A disposable fluid administration system in accordance with claim 23, in which the twin valves are duckbill valves.
 27. A disposable fluid administration system in accordance with claim 23, in which the passage for delivery of fluid is in alignment with the passage to which the syringe is attached, and the passage connected to the fluid supply is at right angles to said passage.
 28. A disposable fluid administration system in accordance with claim 23, in which the interior volume of the coupling body between the valves is less than 1 cc.
 29. A disposable fluid administration system in accordance with claim 23, in which the coupling body is formed of molded plastic.
 30. A disposable fluid administration system in accordance with claim 23, in which the coupling body is made of a relatively rigid plastic.
 31. A disposable fluid administration system in accordance with claim 23, in which the check valve is associated with a resilient foam spring to ensure a leak-tight seal when the valve is closed.
 32. A disposable fluid administration system in accordance with claim 23, including a syringe attached to the T-connector.
 33. A disposable fluid administration system in accordance with claim 23, including an air spring associated with and on the upstream side of the air eliminator.
 34. A disposable fluid administration system in accordance with claim 33, wherein the air spring comprises a chamber, and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by pumping action of the syringe.
 35. A disposable fluid administration system in accordance with claim 34 wherein the chamber walls are of transparent or translucent material.
 36. A disposable fluid administration system in accordance with claim 34 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.
 37. A disposable fluid administration system in accordance with claim 23 comprising a visual flow indicator on the upstream side of the T-connector.
 38. A sterile disposable fluid administration system that is especially designed for use with a syringe having a plunger adapted to be reciprocated by a syringe pump drive, and that prevents administration of air into a patient, comprising, in combination and in series, a twin valve T-connector having a coupling body of plastic material having three interconnected passages therein; check valves in two of said passages controlling flow of fluid therethrough in a single direction, said check valves each comprising a valve member of rubbery material having retaining means thereon held in a fixed position in its passage in a leaktight seal and moveable in a flex action movement at a peripheral portion thereof to engage a valve seat or like valve member in a relatively leaktight seal so as to close the passage and to crack open in a flex action movement with respect to the fixed portion away from the valve seat or like valve member, said valve member presenting a surface exposed and responsive to fluid pressure on each side thereof and being responsive to a fluid pressure on one side tending to bias the valve member against the valve seat or like valve member in a leaktight seal therewith and thus prevent flow from that side, and being responsive to fluid pressure on the other side to move away from the valve seat or like valve member and thus permit flow from that side at the crack-open pressure and thereafter; a fitting insert in each valve-containing passage of a plastic material which is the same as or compatible with the plastic material of the coupling body, the fitting insert extending into the said passage from the outside of the coupliNg body, and having a central passage therethrough for passage of fluid into and out from the T-connector, each fitting insert engaging the valve in its passage so as to capture the retaining means on the valve between the body and the insert, and having a peripheral sidewall abutting the sidewalls of the passage and being bonded with the material of the coupling body forming a leaktight barrier, the fitting insert thus retaining the valve in the coupling body in a permanent leaktight fit, the passage that does not include a check valve being adapted to be attached to a syringe having a plunger adapted to be reciprocated by a pump drive, an air eliminator attached to one of the passages including a check valve, the two check valves together controlling flow of fluids through the system in a direction from the syringe on the pumping stroke of the plunger towards the air eliminator and a delivery means on the downstream side of the air eliminator, all interconnected by fluid delivery tubing in an air- and liquid-tight manner.
 39. A disposable fluid administration system in accordance with claim 38 including a syringe attached to the T-connector.
 40. A disposable fluid administration system in accordance with claim 38 including an air spring associated with and on the upstream side of the air eliminator.
 41. A disposable fluid administration system in accordance with claim 40 wherein the air spring comprises a chamber and an inlet communicating the chamber with the upstream side of the air eliminator, both dimensioned to absorb at least in part pressure surges created by the pumping action of the syringe.
 42. A disposable fluid administration system in accordance with claim 40 wherein the chamber walls are of transparent or translucent material.
 43. A disposable fluid administration system in accordance with claim 41 wherein the chamber walls are provided with a visual scale correlating fluid advance in the chamber with fluid pressure.
 44. A disposable fluid administration system in accordance with claim 42 comprising a visual flow indicator on the upstream side of the T-connector. 